hey everyone! :) i am making a seafood pasta for dinner, and I need some help!!!

Just a thought, check your grocery store for clam juice... in my Publix, it is near the canned tuna and sardines (along with canned clams, of course).

Hopefully your shrimp and mussels still have their shells on them. If this is the case, steam them in a mixture of water and wine, along with some chopped garlic, onion, and celery until done. Once you have peeled and shucked the cooked seafood, add those peels back into the steaming pot along with enough water to make up the amount of broth you will require. Let it simmer for 10-15 minutes, then strain out all the solids and save the liquid. Add the cooked seafood into your pasta and sauce a minute or so before serving, so they will rewarm without overcooking. As a rule, a white clam sauce is just a mixture of white wine, garlic, herbs, and olive oil or butter- so this should work fine. You can thicken it slightly with a bit of cornstarch before adding it to your pasta as well, to give your sauce a bit of body. I don't think I'd want to use chicken stock in a seafood pasta sauce except as a last resort, and I wouldn't use beef stock at all. If all else fails, and you have neither shrimp in peels or mussels in shells, then I would opt to make a white wine/garlic/butter instead- and add the cooked seafood in just before serving. Keep it simple, whatever you do, so the flavor of the seafood isn't lost in a sea of cream and cheese.